The aim of this project is to locate the gene for human neuraminidase on the gentic map. To this end subjects with neuraminidase deficiency (neu-1a, sialidosis already diagnosed by other investigators, will be the probands in family studies. Primary interest lies in the probability that the locus for neu-1a lies within a few centimorgans from the major histocompatibility locus, possibly telomeric to HLA-A. From probands and from all consenting adult relatives blood and skin biopsies are to be obtained. Blood is to be used for haplotyping of HLA, B, and C, as well as of GLO1 and PGM3; for ISO-DALT electrophoresis of proteins, and for assay and typing of sialytransferases. Fibroblasts from skin biopsy are to be used for neuraminidase assay and ISO-DALT electrophoresis of proteins. The purpose in this study is to improve mapping of a gene for a form of affective disorder, a consequence of work by PI published and in press.